A Bit Puzzled About Wireless Modem Placement

Discussion in 'General Electronics Chat' started by PGB1, May 19, 2016.

  1. PGB1

    Thread Starter Member

    Jan 15, 2013
    58
    3
    Hi All!
    This is a very elementary question, so I hope you don't mind the post.
    I had to get a new internet gateway device. It is a gateway & router combination & has wireless capability. In the instructions, the author mentioned that the unit should be placed as high in the house as possible & above all receiving devices for the best signal coverage of the wireless.

    I tried to do my own research and came up with all kinds of conflicting reasons, from curve of the earth, to gravity to air currents from the furnace.

    I learned long ago that an antenna that transmits over long distances should be as high as possible to have line-of-site versus the curve of the earth. (At least I think I learned correctly.) But, a WiFi antenna in a house is transmitting over a short distance, thus no big curve.

    The antenna in the device is internal. I assume it is omni-directional. I picture the signal in the shape of a kind of a sphere. So to my mind, it seems that the antenna would give the building the best signal coverage if it is vertically between the receiving devices. Horizontally, too I suppose. (Example- In a three story house, the antenna should be in the middle floor so the signal is the same on the floor above as it is on the floor below.)

    Would not placing the unit on the top floor, as the directions mentioned, send half of the signal up and out of the house? Conversely, placing in in the basement would send half of the signal into the earth below the floor?

    What do you all think? Am I way off in my thinking on this concept?

    Thanks For The Education!
    Paul
     
  2. #12

    Expert

    Nov 30, 2010
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    Plug it in and find out. You might have a sphere shape, a hemisphere, or a doughnut, depending on the type of antenna. If it's a hemisphere, the basement ceiling is the right answer! Or upside down, hanging from the highest ceiling. One thing I would bet is that the antenna isn't going to radiate energy through the ground planes of the circuit board next to it, so you simply must have weak areas of radiation. This is a near field problem. The things you read about public broadcast transmitters with ideal antennas don't apply in a strict sense. My router didn't work in the laundry room because there was a brick wall in the way. I drilled a hole, moved it 1 foot away (into the kitchen) and it worked. My old router had a stick shaped antenna. The new one has three strange shaped pieces of sheet metal for antennas, but none on the 4th side. You're just going to have to do some tests.
     
  3. WBahn

    Moderator

    Mar 31, 2012
    17,748
    4,796
    Making an omnidirectional antenna is a lot harder than it sounds. The antenna in that unit is designed to work best when the unit is placed according to the instructions.

    One thing that they may try to do is have the radiation pattern be hemispherical downward so that they can get higher power density in the direction that other devices are located while reducing the signal that radiates up and out of the structure where it is both unusable to the devices in the house and a source of interference for devices outside the house.
     
  4. SLK001

    Well-Known Member

    Nov 29, 2011
    819
    228
    I would imagine that there are two folded inverted F antennas mounted orthogonal to each other in the router. I had one folded F in my TV that couldn't catch signals reliably from my router if its life depended on it. I took the inverted F off the wireless card and replaced it with a 1.25" piece of 18ga buss wire. It now gives me 5 bars all the time.
     
  5. Marley

    Member

    Apr 4, 2016
    144
    40
    "curve of the earth, gravity, air currents" what!!

    You are talking Wi-Fi here it only has a short range. Best to place the router it in the middle of the house if possible then it will have the best chance of reaching all rooms. Depends how big your house is, obviously. Not always possible because the incoming line is usually on an outside wall. Sometimes better not to use the Wi-Fi on the router but run a length of CAT5 to a separate Access Point in a central position.

    Brick and concrete walls are the biggest problem. The radio signals are greatly attenuated through these. Depends on the thickness. Another problem can be walls and ceilings covered with foil-backed plasterboard. Also insulating sheets covered in foil. You may not know they are there.

    Definitely experiment.
     
  6. PGB1

    Thread Starter Member

    Jan 15, 2013
    58
    3
    Thank You All for taking time to provide the great explanations & information.
    This is very interesting and, thanks to you all, makes the concept easier to understand.

    What you said, WBanh, about how the engineers designed the antenna for a hemispherical pattern radiating downward made me curious. So, I looked at user guides for other brands. Some said put the unit high in the building, some in the center floor and my Arris says upper floor. It appears each designer builds differently when it comes to the antenna's designed pattern. Pretty Cool!

    I did experiment around a bit last night & today. (Picture a 1-1/2 story house with basement & no attic) I used the very primitive method of looking at signal bars on a laptop computer and cell phone's WiFi & came up with this:

    When the unit is on the second floor, the signal is very weak in the basement and mediocre on the first floor. When the device is on the first floor, the signal is fairly weak all over the house. When it is in the basement, the signal is strong in the basement & first floor and is fairly strong in on the second floor. And hanging it upside down from the basement ceiling, as #12 mentioned, helped noticeably with strength in the weaker areas.
    Next, for fun, I placed a piece of steel about 18" x 36" (filing cabinet) 18" below the router. I was thinking "ground plane". I didn't see any change in signal strength, but my testing method is primitive, indeed.

    When checking the signal outside, it is poor when the unit is in the basement, but zero when the device is on the first or second floors.
    We do have some aluminum radiant barrier. It is in the ceiling of one room on the second floor and 3 walls of the same room. The other 2nd floor room has no barrier, so I checked outside near that room. (Also, no metal lath under the plaster. All wood)

    My Theories?
    A) Position When Below the Receiving Devices (computers):
    Hanging it upside down is now sending the signal up, instead of down. (Assuming the antenna was designed to send signal down when upright)

    B) Interference:
    If I look at the list of available networks, it is very populated and some of their signals are quite a bit stronger than mine. I am guessing (just guessing) that when my unit is higher up in the house, there is more signal from those units than from mine.

    E) Time Of Day
    In the evening, the signal is weakest. In the daytime, it is stronger even though the same neighboring networks still show as available.
    The only thing I can think of for this is, perhaps, a neighbor was using a 2.4 GHz cordless phone or microwave oven. My devices can't use 5 GHz, so I could not test this idea. (Technically the phone can, but I could not get it to cooperate. I'm new to smart phones.)

    D) Proof Of Concept?
    Just for fun, I went into my back yard & had no signal. (Modem in basement). I propped open the steel main door & the aluminum screen door. Then I had a medium signal. So, the signal went through the opening easily, but struggles getting through the house wall. (Modem & computer were not in line-of-sight of the opening or each other)
    I guess that one should have been obvious, but I had to prove ti to myself.

    Did I get the theories correct?

    Next, I'll experiment with changing channels on the router to see if that helps my signal.
    If I can't get a consistently usable signal, I'll further investigate the separate Access Point that you mentioned, Marley. From what I have read, that sounds quite promising.

    Thanks Again All For The Education! I like learning (can't hurt, right?)
    Enjoy This Day!
    Paul
     
  7. MrSoftware

    Active Member

    Oct 29, 2013
    501
    123
    Wi-Fi is relatively high frequency, 2.4GHz or more, and therefore does not penetrate well. IMHO, give up on trying to find the magical location and get a wireless access point or two. The commercial ones aren't that expensive, look like nice smoke detectors and work extremely well.
     
  8. #12

    Expert

    Nov 30, 2010
    16,298
    6,810
    That's why you can choose different "channels".
    Oh. You figured that out.:oops:

    My neighbor across the street and 2 houses down has something with the word, "Airport" in it's name. His signal is as strong at my house as my own signal!
    Apple Airport Extreme? Something like that. Maybe you can change your purchase.
     
  9. PGB1

    Thread Starter Member

    Jan 15, 2013
    58
    3
    Thanks Again All for your help!
    It never dawned on me that 2.4 is high enough not to penetrate well- kind of like how microwave ovens keep the signal inside the oven. I assume the reason the oven's window has the viewing window has the screen in it is so the waves can't escape. (I picture the magnetron throwing a handful of toothpicks at the window & they are too short to align themselves to find their way out of the holes.)

    The network list on my computer also shows an Apple Airport Extreme form somewhere. They must be super powered or something.
    I read a lot about various models of routers and what peoples' results were. I read about antenna options, but that seems like something I won't need. I also have been reading & learning about access points. They seem to be a much better option than a repeater.
    When I was still working full time as an electrician I had to install a lot of circuits & run a lot of CAT-5e wiring so the IT people could install a device that I never asked about. That job was in the early 1990s. I have to believe they were the access points since they were strategically placed about the building. (It was a really big & all concrete NFL stadium. We also put in lots of repeaters for UHF- Those I understood.)

    I've learned a lot & will explore access points versus a different router.

    Thanks Again & Enjoy This Day!
    Paul
     
  10. Marley

    Member

    Apr 4, 2016
    144
    40
    Don't forget Wi-Fi is 2-way communication. No good having a powerful access point if your laptop/tablet/phone is not powerful enough to communicate the other way! On a large building I would definitely have more than one access point.
     
  11. PGB1

    Thread Starter Member

    Jan 15, 2013
    58
    3
    Thanks Marley. That must be why I had to install so many of the devices in the stadium.
    Enjoy Today!
    Paul
     
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